Many people often have trouble managing more than one mobile phone number, since it traditionally requires having a separate phone for each SIM card associated with a phone number. People have gone around this by swapping out SIM cards from a single phone, or by purchasing dual-SIM card phones.
More recently, there have been advancements in SIM card technology, allowing users to store multiple phone numbers on a single SIM card, however such systems require users to manually change phone numbers by removing the SIM card, using a SIM card reader connected to a computer and a computer application to manually switch phone numbers, which remains a cumbersome and inconvenient task.